The most difficult choice in Rc boating is picking the perfect prop!

Propellers come in many different materials, listed from softest to hardest are Plastic, Aluminum, Carbon Fiber, Beryllium Copper, and Stainless Steel. The best performance will be from a perfectly balanced and sharpened Beryllium Copper or Stainless Steel prop. You'll notice the the bellow pictures of the Beryllium Copper & Stainless steel props are very dull, that's because these props come as castings and need to be filed, sharpened & balanced. See How to Balance and Sharpen Article for more information. For the best "bang for the buck" and no work balancing & sharpening, look at the Graupner Carbon Filler Propellers. They are great for Sport running. 
 

When searching for the perfect prop we need to balance three important factors, Top Speed, heat buildup in Batteries, Motor & ESC (electronic speed control) and the ability for the hull to get up on plane.  Most Electric kit boats come with props that will work in a wide range of applications. Changing to the right prop with a kit boat will almost always yield a performance increase. Always start out with a smaller prop and work up to the optimum size. Never put to large of a prop an electric boat first. This will lead to burnt up ESC, Motor or Batteries. Bigger is not better in every case, this is particularly true in high RPM motors. To run at their best efficiency they need  to spin fast. Too large of a prop will not allow the prop to reach its best RPM efficiency range and will cause heat build up in the ESC, Motor or Batteries. On the first run with the new prop, run it at full speed for twenty to thirty seconds, observe how quickly the boat got on plane and the top speed, the pull the boat out of the water and to test for heat, have an adult give the motor the 5 second test. Which is, hold your finger on the motor for 5 seconds. If its so hot you can't hold it for 5 seconds, its too hot. Allow to cool fully before running again! If everything is cool or warm, keep doing this test until the pack starts to dump. DO NOT RUN THE PACK TO 0% CAPACITY! This will cause lots of heat and ruin your test results. At the end of the run if things are warm but not hot swap to a larger prop. With  Nitro, running too small a prop may allow the engine to spin at to high of an RPM and blow the engine!

Things to remember

• First move the COG (center of gravity) forward or backward to get on plane quicker. For most monos and catamarans 30% forward of the transom is a good place to start. To check the COG put your left and right finger 1/3 of the hull length forward of the transom and have the boat balance in your fingers.
• If the boat will not come on plane, and the motor seems to be at full RPM the prop is  cavitating. You may need a larger prop with more thrust to get on plane.
• A well balanced and sharpened prop will always spin at higher RPM allowing a higher top speed!
• Always monitor motor or engine heat! Cooler is better. To much heat kills!
• Different water conditions will achieve different results. When comparing test results from a different day make sure the water and wind conditions where similar!
   

The following Chart is from Octura's line up of Propellers. There are other companies that offer propellers but Octura seems to have the widest range of sizes for Electrics. Most props are left hand props, except for the ones labeled with an "R" after the prop Size.

To figure out how far a particular prop will travel, we need to know the total pitch, which is the diameter x pitch.
If we take into example the first prop listed(930), 1.18"diameter X .9 pitch = 1.062"
So the total pitch of the 930 prop is 1.062 inches. Every time the prop shaft turns once the boat will move 1.062 inches. This is with no slip in a perfect world. Well it isn't a perfect world so as a rule of thumb,

• A Mono hull will slip 25%
• A Catamaran of scale Hydro 20%
• A Rigger about 15%

This is assuming that the hulls are well balanced and running free.

Click here for a Tool to make some top speed estimates!
 

Octura Propellers.
Prop#	Diameter	Pitch	Fits shaft size	Plastic	Al	BC
930	30mm (1.18")	0.9 x 1.18 =1.062"	1/8"		x	x
937/3	37mm (1.48")	0.9 x 1.48 =1.332"	1/8"		x	x
955/3	55mm (2.17")	0.9 x 2.17 =1.953"	3/16"			x
0955/3R	55mm (2.17")	0.9 x 2.17 =1.953"	3/16"			x
977	77mm (3.03")	0.9 x 3.03 =2.727"	1/4"			x
1240	40mm (1.57")	1.2 x 1.57 =1.884"	3/16"	x
1240/3	40mm (1.57")	1.2 x 1.57 =1.884"	3/16"			x
1245	45mm (1.77")	1.2 x 1.77 =2.124"	3/16"	x
1250	50mm (1.97")	1.2 x 1.97 =2.364"	3/16"	x
1250R	50mm (1.97")	1.2 x 1.97 =2.364"	3/16"	x
1255	55mm (2.17")	1.2 x 2.17 =2.604"	3/16"	x
1270	70mm (2.76")	1.2 x 2.76 =3.312"	3/16"	x
1337/3	37mm (1.48")	1.3 x 1.48 =1.924"	3/16"			x
1427	27mm (1.07")	1.4 x 1.07 =1.498"	1/8"		x	x
1435	35mm (1.38")	1.4 x 1.38 =1.932"	3/16"	x
1440	40mm (1.57")	1.4 x 1.57 =2.198"	3/16"	x
1445	45mm (1.77")	1.4 x 1.77 =2.478"	3/16"	x
1450	50mm (1.97")	1.4 x 1.97 =2.758"	3/16"	x		x
1455	55mm (2.17")	1.4 x 2.17 =3.038"	3/16"	x		x
1455/3	55mm (2.17")	1.4 x 2.17 =3.038"	3/16"			x
1457	57mm (2.24")	1.4 x 2.24 =3.136"	3/16"	x		x
1457R	57mm (2.24")	1.4 x 2.24 =3.136"	3/16"	x
1457/3	57mm (2.24")	1.4 x 2.24 =3.136"	3/16"			x
1460	60mm (2.36")	1.4 x 2.36 =3.304"	3/16"	x		x
1462	62mm (2.44")	1.4 x 2.44 =3.416"	3/16"	x		x
1462R	62mm (2.44")	1.4 x 2.44 =3.416"	3/16"	x
1465	65mm (2.56")	1.4 x 2.56 =3.584"	3/16"	x		x
1467	67mm (2.64")	1.4 x 2.64 =3.696"	1/4"			x
1470	70mm (2.76")	1.4 x 2.76 =3.864"	3/16"	x
1470	70mm (2.76")	1.4 x 2.76 =3.864"	1/4"			x
1475	75mm (2.95")	1.4 x 2.95 =4.130"	1/4"			x
1540	40mm (1.57")	1.5 x 1.57 = 2.355"	3/16"			x
1567	67mm (2.64")	1.5 x 2.64 = 3.960"	1/4"			x
1630	30mm (1.18")	1.6 x 1.18 = 1.888"	1/8"		x	x
1640	40mm (1.57")	1.6 x 1.57 = 2.512"	3/16"			x
1650	50mm (1.97")	1.6 x 1.97 = 3.152"	3/16"			x
1655	55mm (2.17")	1.6 x 2.17 = 3.472"	3/16"			x
1657	57mm (2.24")	1.6 x 2.24 = 3.584"	3/16"			x
1662	62mm (2.44")	1.6 x 2.44 = 3.904"	3/16"			x
1667	67mm (2.64")	1.6 x 2.64 = 4.224"	1/4"			x
1732	32mm (1.26")	1.7 x 1.26 = 2.142"	1/8"		x	x
1735	35mm (1.38")	1.7 x 1.38 = 2.346"	1/8"			x
1740	40mm (1.57")	1.7 x 1.57 = 2.669"	3/16"			x
1740/3	40ma (1.57")	1.7 x 1.57 = 2.669"	3/16"			x
1742/3	42mm (1.65")	1.7 x 1.65 = 2.805"	3/16"			x
1745/3	45mm (1.77")	1.7 x 1.77 = 3.009"	3/16"			x
1747	47mm (1.85")	1.7 x 1.85 = 3.145"	3/16"			x
1750	50mm (1.97")	1.7 x 1.97 = 3.349"	3/16"			x
1752/3	52mm (2.05")	1.7 x 2.05 = 3.485"	3/16"			x
1755	55mm (2.17")	1.7 x 2.17 = 3.689"	3/16"			x
1760	60mm (2.36")	1.7 x 2.36 = 4.012"	3/16"			x
1860	60mm (2.36")	1.8 x 2.36 = 4.248"	3/16"			x
1930	30mm (1.18")	1.9 x 1.18 = 2.242"	1/8"		x	x
1938	38mm (1.50")	1.9 x 1.50 = 2.850"	3/16"			x
1945	45mm (1.77")	1.9 x 1.77 = 3.363"	3/16"			x
1950	50mm (1.97")	1.9 x 1.97 = 3.743"	3/16"			x
1950/3	50mm (1.97")	1.9 x 1.97 = 3.743"	3/16"			x
1955	55mm (2.17")	1.9 x 2.17 = 4.123"	3/16"			x
1957	57mm (2.24")	1.9 x 2.24 = 4.256"	3/16"			x
1967	67mm (2.64")	1.9 x 2.64 = 5.016"	1/4"			x
2035	35mm (1.38")	2.0 x 1.38 = 2.760"	3/16"	x
2045	45mm (1.77")	2.0 x 1.77 = 3.540"	3/16"	x
2047	47mm (1.85")	2.0 x 1.85 = 3.700"	3/16"			x
2050	50mm (1.97")	2.0 x 1.97 = 3.964"	3/16"	x
2055	55mm (2.17")	2.0 x 2.17 = 4.340"	3/16"	x
2060	60mm (2.36")	2.0 x 2.36 = 4.720"	3/16"	x
2137/3	37mm (1.48")	2.1 x 1.48 = 3.108"	3/16"			x
2150/3	50mm (1.97")	2.1 x 1.97 = 4.137"	3/16"			x
2160	60mm (2.36")	2.1 x 2.36 = 4.956"	3/16"	x		x
2167/3	67mm (2.64")	2.1 x 2.64 = 5.544"	1/4"			x
2250	50mm (1.97")	2.2 x 1.97 = 4.334"	3/16"			x
2260	60mm (2.36")	2.2 x 2.36 = 5.192"	3/16"			x
2267	67mm (2.64")	2.2 x 2.64 = 5.808"	1/4"			x
2352	52mm (2.05")	2.3 x 2.05 = 4.715"	3/16"			x
M447	47mm (1.85")	1.4x1.85=2.590"	3/16"			x
P735	35mm (1.38")	1.7x1.38=2.346"	1/8"		x	x
P747	47mm (1.85")	1.7x1.85=3.145"	3/16"			x
P767/3	67mm (2.64")	1.7x2.64=4.488"	1/4"			x
V937/3	37mm (1.48")	1.9x1.48=2.812"	3/16"			x
V947/3	47mm (1.85")	1.9x1.85=3.515"	3/16"			x
V955/3	55mm (2.17")	1.9x2.17=4.123"	3/16"			x
V967/3	67mm (2.64")	1.9x2.64=5.016"	1/4"			x
X427	27mm (1.07")	1.4x1.07=1.498"	1/8"		x	x
X430	30mm (1.18")	1.4x1.18=1.652"	1/8"		x	x
X430R	30mm (1.18")	1.4x1.18=1.652"	1/8"		x	x
X431	3lmm (1.22")	1.4x1.22=1.708"	1/8"	x
X432	32mm (1.26")	1.4x1.26=1.764"	1/8"		x	x
X435	35mm (1.38")	1.4x1.38=1.932"	1/8"		x	x
X437/3	37mm (1.48")	1.4x1.48=2.072"	3/16"		x	x
X438	38mm (1.50")	1.4x1.50=2.100"	3/16"		x	x
X440	40mm (1.57")	1.4x1.57=2.198"	3/16"		x	x
X440/3	40mm (1.57")	1.4x1.57=2.198"	3/16"		x	x
X442	42mm (1.65")	1.4x1.65=2.310"	3/16"		x	x
X445	45mm (1.77")	1.4x1.77=2.478"	3/16"		x	x
X447	47mm (1.85")	1.4x1.85=2.590"	3/16"		x	x
X447R	47mm (1.85")	1.4x1.85=2.590"	3/16"		x	x
X447/3	47mm (1.85")	1.4x1.85=2.590"	3/16"		x	x
X448	48mm (1.90")	1.4x1.90=2.660"	3/16"		x	x
X450	50mm (1.97")	1.4x1.97=2.758"	3/16"		x	x
X450/3	50mm (1.97")	1.4x1.97=2.758"	3/16"			x
X452	52mm (2.05")	1.4x2.05=2.870"	3/16"			x
X452/3	52mm (2.05")	1.4x2.05=2.870"	3/16"			x
X455	55mm (2.17")	1.4x2.17=3.038"	3/16"			x
X455/3	55mm (2.17")	1.4x2.17=3.038"	3/16"			x
X457	57mm (2.24")	1.4x2.24=3.136"	3/16"			x
X457R	57mm (2.24")	1.4x2.24=3.136"	3/16"			x
X457/3	57mm (2.24")	1.4x2.24=3.136"	3/16"			x
X460	60mm (2.36")	1.4x2.36=3.304"	3/16"			x
X460/3	60mm (2.36")	1.4x2.36=3.304"	3/16"			x
X462	62mm (2.44")	1.4x2.44=3.416"	3/16"			x
X465	65mm (2.56")	1.4x2.56=3.584"	3/16"			x
X465R	65mm (2.56")	1.4x2.56=3.584"	3/16"			x
X467	67mm (2.64")	1.4x2.64=3.696"	1/4"			x
X470	70mm (2.76")	1.4x2.76=3.864"	1/4"			x
X47OR	70mm (2.76")	1.4x2.76=3.864"	1/4"			x
X470/3	70mm (2.76")	1.4x2.76=3.864"	1/4"			x
X472	72mm (2.84")	1.4x2.84=3.976"	1/4"			x
X482	82mm (3.22")	1.4x3.22=4.508"	1/4"			x
X548	48mm (1.90")	1.5x1.90=2.850"	3/16"			x
X560	60mm (2.36")	1.5x2.36=3.540"	3/16"			x
X572	72mm (2.84")	1.5x2.84=4.260"	1/4"			x
X632	32mm (1.26")	1.6x1.26=2.016	1/8"		x	x
X637	37nun (1.48")	1.6x1.48=2.368"	3/16"		x	x
X640	40mm (1.57")	1.6x1.57=2.512"	3/16"		x	x
X642	42mm (1.65")	1.6x1.65=2.640"	3/16"		x	x
X645	45mm (1.77")	1.6x1.77=2.832"	3/16"		x	x
X646	46mm (1.81")	1.6x1.81=2.896"	3/16"		x	x
X646/3	46mm (1.8")	1.6x1.81=2.896"	3/16"			x
X648	48mm (1.90")	1.6x1.9=3.040"	3/16"		x	x
X665	65mm (2.56")	1.6x2.56=4.096"	3/16"			x
X665R	65mm (2.56")	1.6x2.56=4.096"	3/16"			x
X670	70mm (2.76")	1.6x2.76=4.416"	1/4"			x
Y535	35mm (1.38")	2.125"	1/8"		x	x
Y547	47mm (1.85")	2.849"	3/16"			x
Y557	57mm (2.24")	3.449"	3/16"			x
Z50	50mm (1.97")	1.6x1.97=3.152"	3/16"	x
Z55	55mm (2.17")	1.6x2.17=3.472"	3/16"	x
Z60	60mm (2.36")	1.6x2.36=3.776"	3/16"	x
1.6	1.6"	1.8x1.6=2.880"	3/16"	x		x
1.6/3	1.6"	1.8x1.6=2.880"	3/16"			x
1.8	1.8"	1.8x1.8=3.240"	3/16"	x		x
2.0	2"	1.8x2=3.600"	3/16"	x
2.0/4	2"	1.8x2=3.600"	3/16"			x
2.1/3	2.1"	1.8x2.1=3.780"	3/16"			x
2.2	2.2"	1.8x2.2=3.960"	3/16"	x
2.4	2.4"	1.8x2.4=4.320"	3/16"	x
2.4/3	2.4"	1.8x2.4=4.320"	1/4"			x
2.6	2.6"	1.8x2.6=4.680"	3/16"	x
2.8	2.8"	1.8x2.8=5.040"	3/16"	x

 

Graupner Carbon Fiber Propellers.
Prop	Diameter	Pitch	Fits shaft size	Carbon Fiber
2317.40	40mm(1.57")	1.4x40=56.0mm or 2.20"	3/16"	x
2317.42	42mm(1.65")	1.4x42=58.8mm or 2.31"	3/16"	x
2317.45	45mm(1.77")	1.4x45=63.0mm or 2.48"	3/16"	x
2317.48	48mm(1.89")	1.4x48=67.0mm or 2.64"	3/16"	x
2317.51	51mm(2.01")	1.4x51=71.0mm or 2.80"	3/16"	x

Prather Propellers
Prop#	Diameter	Pitch
215	40.6mm (1.60")	2.5"
220	43.7mm (1.72")	2.6"
225	46.7mm (1.84")	2.8"
230	48.3mm (1.90")	3.0"
235	50.8mm (2.00")	3.2"
240	53.8mm (2.12")	3.3"
245	57.2mm (2.25")	3.5"
250	58.4mm (2.30")	3.6"
255	61.0mm (2.40")	3.8"
260	64.0mm (2.52")	3.9"
265	66.3mm (2.61")	4.0"
270	69.6mm (2.74")	4.2"
275	74.9mm (2.95")	4.3"
280	78.7mm (3.10")	4.5"